As it happens, modern hard drives tend to be more fragile than their predecessors. You can find lots of people using their decade-old PCs, with 80GB Western Digital or 40GB Samsung drives. Those drives were made to withstand the test of time.
At present, we see a great decrease in the lifespan of mechanical drives. With growing capacities and cutting edge technologies, such as SMR, Hybrid, or Helium drives, the amount of things that can go wrong grows as well.
Today I want to talk about “burnt drives.” A burnt drive is a hard drive that was subjected to a power surge, which resulted in damage to one or more of its electrical systems.
What can cause a power surge?
In most cases, that would be a sudden spike in the grid, caused by a lightning storm or malfunction with the PC’s power supply, although many other events could result in damaging the hard drive, starting from the degradation of the PCB (Printed Circuit Board), bad soldering, poor quality of components, moisture, or a user error. Whatever the reason is, once the currents start to rise, they bring high temperatures. And once it’s high enough, a component subjected to those temperatures will burn.
How would you identify a burnt drive?
First of all, the smell and the smoke. Burned electrical parts smell like burned plastic, and that would be the first sign of the damage that occurred.
Visual inspection – The PCB can be easily removed from the hard drive. Upon removal, the burnt parts will be spotted in plain view.
Drive performance – Burnt drive will not spin and will not power on.
What happens to the PCB and the drive once it’s faced with a power surge?
Most modern PCBs are equipped with temperature sensors designed to monitor the PCB temperature, protective diodes built to shield the drive from power surges, and capacitors used to flatten the line of the incoming voltage. Those components serve well, and often they “sacrifice” themselves to save more crucial components of the PCB.
Unfortunately, if the power surge is too powerful, it often damages some of those crucial components, before being terminated.
Often, the damage is extended beyond the PCB and affects a small chip located on the actuator arm of the read/write heads. That small chip is called a preamplifier or preamp. It will result in permanent damage to the read/write heads assembly, and will probably require to have it replaced.
The Printed Circuit Board
To begin with, let us talk about the role of the PCB. It serves as an interface between the data stored on the platters and the computer. It transfers data in and out, controls the operation of the drive, provides power (5V and 12V), and stores some unique information as per the drive. The main components of the Printed Circuit Board are:
MCU – Micro Controller Unit. It would usually be the biggest chip onboard the PCB. The MCU serves as the central processor of the hard drive, controls the flow of the data, and converts digital data coming into the hard drive into analog signals for the read/write heads, and vice versa.
VCM – Voice Coil Motor Controller. In charge of controlling the movement of the heads and the rotation of the spindle motor. The VCM controller is built to withstand high temperatures, as it consumes and transfers the majority of the power used by the HDD. Usually, it’s also one of the first components to burn out.
Diode – The TVS (Transient Voltage Suppression) diode is in place to protect other PCB components from being subjected to power surges. Once a power surge occurs, the diode burns itself, opening the circuit, and creating a short to the ground.
The ROM – This little chip is called ROM (Read Only Memory) in professional jargon, but it functions more like an EPROM (Erasable Programmable ROM) – it means that its contents can be erased and reprogrammed. It contains a very important part of the drive’s firmware, and without it, the drive would not function properly. The part of the software contained within the ROM is unique to the drive it’s installed on. That is why if you are looking to repair your drive by installing a new PCB instead of a burnt one, your drive will not resume its normal function.
Sometimes, you will see PCBs without the ROM chip. That means that the data usually contained by the ROM is embedded in the MCU.
What can you do when your PCB sustains irreversible damage?
As we can derive from the explained above, simply replacing the PCB for a new one won’t cut it. The data contained in the ROM of an old PCB must be transferred onto the new donor PCB, to have the drive working.
That can be done in one of the following ways:
- By physically moving the original ROM chip onto the new donor PCB. For that step, minimal soldering skills and equipment are required. The ROM chip has only 8 legs and can be easily transferred from one PCB to another.
- By reading the ROM from the PCB using a professional data recovery tool, such as PC3000. Often, if the PCB is not completely fried, it maintains some kind of minimal functionality, thus allowing the tool to read the ROM data from it. After reading and storing the ROM, it can be flashed onto a donor PCB, using the same tool.
- As a last resort, assuming the original PCB is lost or damaged beyond repair, the PC3000 tool can sometimes rebuild the contents of the ROM by using various data modules taken from the original drive. That process only works with some HDD vendors and requires a good amount of skills and expertise using PC3000, as well as a good understanding of the HDD Service Area structure and functionality.
When attempting any DIY solution, one must always consider the risks involved. On one side, it feels great to accomplish a complicated repair, not to mention the nice side effect of saving some time and money. On the other side, there is always a chance of causing additional damage up to the level when even a professional data recovery specialist won’t be able to help. Over the years, I had seen cases when clients damaged the ROM chip by overheating it or by breaking one of its legs, and when that happens, there is no way back. Yes, for some WD models, you can potentially rebuild the ROM, but if you have a Seagate or Hitachi, the chances to ever see your data are extremely slim.
If you’ve decided to attempt your repair, please consider the outcomes. If you cannot afford to lose your data, perhaps it’s better to let a data recovery company handle it.
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